<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>bootstrap--button</title>
    <link rel="stylesheet" href="./bootstrap/css/bootstrap.min.css">
    <style>
        .btn-success{
            width: 80px;
        }
    </style>
</head>

<body>
123
<button type="button" class="btn btn-success">Success</button>
<div class="btn  btn-success">div</div>
<div class="btn  btn-danger" style="width: 100px;">div</div>
</body>

</html>